A medical implant like a pacemaker or a Deep Brain Stimulation system is a typical example of an electronic apparatus in which electrical power has to be transferred from a DC power storage (battery) to power-consuming circuits. Due to its operation in a wet environment, care must be taken to avoid harmful effects like electrolysis when electronic components of an implant come into contact with moisture. In the U.S. Pat. No. 3,888,260, this is achieved by providing an implant with a double hermetic sealing. However, when the battery of an implant shall be replaced at the end of its lifetime, it is difficult to do this without permanently damaging such a sealing.